III-Nitrides Resonant Cavity Photodetector Devices

Abstract

III-nitride resonant cavity-enhanced Schottky barrier photodetectors were fabricated on

2 µm thick GaN templates by radio frequency plasma-assisted molecular beam epitaxy. The optical

cavity was formed by a bottom distributed Bragg reflector based on 10 periods of Al0.3Ga0.7N/GaN,

an Au-based Schottky contact as top mirror, and an active zone of 40 nm-thick GaN layer. The devices

were fabricated with planar geometry. To evaluate the main benefits allowed by the optical cavity,

conventional Schottky photodetectors were also processed. The results revealed a planar spectral

response for the conventional photodetector, unlike the resonant devices that showed two raised

peaks at 330 and 358 nm with responsivities of 0.34 and 0.39 mA/W, respectively. Both values were

80 times higher than the planar response of the conventional device. These results demonstrate the

strong effect of the optical cavity to achieve the desired wavelength selectivity and to enhance the

optical field thanks to the light resonance into the optical cavity. The research of such a combination

of nitride-based Bragg mirror and thin active layer is the kernel of the present paper.